Food safe knife blackening

[Shigs]

Hey all! Totally new and learning, bear with me! I've done a lot of searching but haven't really found an answer. I'm looking to blacken some chef's knives, what methods are actually food safe??

 

[Smiling]

I would say vinegar.

 

[Alberta Ed]

Just use them. High carbon steel will acquire a patina over time. Stainless cutlery grades will not go as dark although they may discolor slightly.